Solve for $x$ : $10\sqrt{x} + 9 = 7\sqrt{x} + 6$
Solution: Subtract $7\sqrt{x}$ from both sides: $(10\sqrt{x} + 9) - 7\sqrt{x} = (7\sqrt{x} + 6) - 7\sqrt{x}$ $3\sqrt{x} + 9 = 6$ Subtract $9$ from both sides: $(3\sqrt{x} + 9) - 9 = 6 - 9$ $3\sqrt{x} = -3$ Divide both sides by $3$ $\frac{3\sqrt{x}}{3} = \frac{-3}{3}$ Simplify. $\sqrt{x} = -1$ The principal root of a number cannot be negative. So, there is no solution.